How to avoid pinching when constructing joint topology?
Topology alone will not do much for you. It's about how the bones influence/deform the topology.

To minimize pinching in such areas you can do 4 things:


Use Corrective Smooth modifier after the Armature modifier. This is designed for this problem (new in Blender 2.75). Use the vertex group input to influence what regions to smooth.
Change the bones point of rotation (this will change the radius at which the vertices rotate when bone rotates).
Smooth the deformation influence - couple options:


smooth bone weights or smooth them across multiple bones
use low-poly lattice or mesh deform to deform the mesh, deform the lattice/meshdeform with armature - this smooths the deformation

Use corrective shapekeys driven by bones.